US 20050144845 A1
A high structural load window sash latch includes a load applying housing wrap that extends around the interior face of a window sash. The housing wrap transfers the majority of positive forces incident upon the sash to a latch housing, where the forces are transferred to a latch bolt and then to the window jamb. Further, two load-bearing screws also secure the latch housing to the sash, while a hold down screw prevents the housing from lifting.
1. A window sash latch for securing a window sash to a window jamb comprising:
a movable latch bolt adapted to interface with the window jamb;
a latch housing, the latch housing including:
a) a channel that at least partially surrounds the latch bolt, the channel permitting horizontal travel of the latch bolt such that the latch bolt may be extended into, or retracted from, the window jamb, the channel restraining the latch bolt from movement in one or more other directions, and
b) a housing wrap integral to the latch housing, the housing wrap extending around and down a portion of an interior face of the window sash; and
one or more fasteners for interconnecting the latch housing and the window sash,
wherein the latch housing and integral housing wrap operate to transfer force between the window sash and the window jamb through the latch bolt.
2. The window sash latch of
a spring attached to the latch bolt and adapted to hold the latch bolt extended into the window jamb.
3. The window sash latch of
4. The window sash latch of
5. The window sash latch of
6. The window sash latch of
7. The window sash latch of
8. The window sash latch of
9. The window sash latch of
10. The window sash latch of
11. The window sash latch of
12. A window sash latch for securing a window sash to a window jamb comprising:
a movable latch bolt adapted to interface with the window jamb;
a housing wrap, positioned on a top surface of the window sash and extending around and down a portion of an interior face of the window sash, the housing wrap including one or more upwardly extending vertical ears that provide a path for the latch bolt to travel horizontally in, such that the latch bolt may be extended into, or retracted from, the window jamb, the vertical ears further restraining the bolt from movement in one or more other directions;
a separate latch housing at least partially surrounding the latch bolt; and
one or more fasteners interconnecting the housing wrap, latch housing, and window sash,
wherein the housing wrap operates to transfer force between the window sash and the window jamb through the latch bolt.
13. The window sash latch of
14. A window sash latch for securing a window sash to a window jamb comprising:
means for latching attached to the window sash, the means for latching adapted to interface with the window jamb;
means for providing a path for horizontal travel of the means for latching, such that the means for latching may move along the path to extended into, or retracted from, interfacing with the window jamb, the means for providing a path further preventing the means for latching from moving in one or more other directions; and
a housing wrap that extends around and down a portion of an interior face of the window sash,
wherein the housing wrap operates to transfer force between the window sash and the means for latching
15. The window sash latch of
means for fastening the housing wrap to the window sash.
The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/534,582, which was filed on Jan. 6, 2004, by Ed Heck and Jimmie D. Daniels, Jr. for a HIGH STRUCTURAL LOAD WINDOW SASH LATCH and is hereby incorporated by reference.
1. Field of the Invention
The invention relates generally to the construction of exterior windows suitable for use in commercial or residential buildings. In particular, the invention relates to a latching mechanism for window sashes that allows the sashes to withstand high forces, such as the wind forces that occur during storms.
2. Background Information
Exterior windows are designed to provide a weather-tight barrier against the elements. During most weather conditions, windows are subject to only nominal forces. These forces can easily be withstood by conventional window designs. Yet, during severe weather, exterior windows may be subject to much greater forces. A category 1 hurricane, the least severe type according to the Saffir-Simpson scale, produces winds in excess of 74 mph. A category 4 hurricane, a more severe type, can produce winds up to 155 mph. Similarly, a mild category F-0 tornado (according to the Fujita scale), produces winds of up to 72 mph, while more powerful tornadoes can generate winds of 260 mph or more.
High speed winds may exert large forces against an exterior window. The magnitude of a wind force is proportional to the square of the wind speed, causing wind force to increase rapidly as wind speed increases. Wind typically exerts two types of force on an exterior window. The first type, a sustained force, is an almost constant force that may last, for example, up to a minute or more. The second type, an intermittent force, is a momentary force created by a higher-speed wind gust and may last up to a few seconds.
Sustained and intermittent forces are often exerted upon exterior windows in multiple directions. Generally, wind blowing against a building creates a positive force (an inward force) on the windward side of the building and a negative force (an outward or suction force) on the leeward side of the building. Depending on the shape of the building, negative forces may also be exerted on walls parallel to the wind. As wind direction shifts, placement of positive and negative forces constantly changes.
Conventional window designs are often ill suited to withstand the severe forces created by hurricanes and tornadoes. While glass breakage is the most common mode of failure, window sashes and frames themselves may fail under force. When a window is subject to extreme forces, a window sash may dislodge from the window jamb. This problem is particularly acute in double-hung windows where the sash travels in a track or channel, and is not attached to the jamb by hinges or other fasteners. Once dislodged from the jamb, a sash may be blown into, or out of, the building, potentially injuring occupants of the building or passersby. Further, wind and water may enter the building through the window opening, damaging the building and its contents.
Latching mechanisms have been designed that purport to better secure window sashes to their jambs. Some of these latching mechanisms employ a bolt device that extends into the window jamb. While providing some benefit, these previous designs have suffered from poor performance. Under high forces, the prior latching mechanisms have tended to lift and separate from sashes, often allowing their bolts to break free and dislodge. When this occurs, the sash may be blown from the jamb despite the latching mechanism.
What is needed is an improved window sash latch that more effectively secures a window sash to a window jamb than the prior designs. Such a window sash latch should better withstand forces incident upon the window sash, and demonstrate superior resistance to separation from the sash. An improved window sash latch must also be easy to operate and relatively inexpensive to manufacture.
The disadvantages of prior window sash latches are overcome by providing a high structural load window sash latch that more effectively transfers forces from a window sash to a window jamb. The new window sash latch consists of a spring-loaded latch bolt that interfaces with the jamb, and a novel housing made from impact-resistant materials. The housing includes a load applying housing wrap that is essentially an extension of the housing that curves around an interior portion of the window sash and absorbs the majority of the positive forces incident upon the sash. These forces are then transferred into the rest of the housing, and, in turn, to the latch bolt and the window jamb.
The high structural load window sash latch may be further held in place by a hold-down screw positioned on the exterior side of the housing, close to where the window sash meets the window jamb. The hold-down screw prevents the housing from lifting away from the sash in response to forces, thus retaining the latch bolt in place and preventing it from sliding under, and out of, the housing. Two additional load bearing screws, located on the interior side of the housing, transfer negative forces incident upon the sash to the housing.
The novel window sash latch effectively transfers forces from the window sash to the window jamb, and thus reduces the risk of a sash dislodging during severe weather. Further, the window sash latch may be employed with conventional sashes, or with sashes that have other structural features suited for withstanding wind forces, such as interlocking meeting rails.
The invention description below refers to the accompanying drawings, of which:
The high load window sash latch further includes a movable latch bolt 110 that slides horizontally in a channel 140 (shown in dashed lines), formed in the housing 150. In one embodiment, the bottom surface of the latch bolt 110 may rest directly upon, and slide along, the top of the window sash. Alternatively, the housing 150 may completely enclose the latch bolt 110, so that latch bolt 110 does not contact the window sash.
The latch bolt 110 may slide inward, so that at one extreme the bolt is retracted close to the side of the window sash 190, allowing the top of the sash to be tilted out for cleaning or other purposes. Likewise, the latch bolt 110 may slide outward, so that, at another extreme, the bolt is extended into the window jamb 450 (
The housing 150 is further secured to the sash by two load-bearing screws 320, 330 located parallel to the interior face of the window sash 190. These screws may transfer negative forces incident on the window sash to the housing, which then transfers the forces to the latch bolt.
As discussed above, the housing wrap 210 effectively transfers the majority of positive forces from the window sash to the housing. Consequently, the housing may be held in place by screws that attach to hollow (non-reinforced) ends of the window sash. Prior window sash latch designs have required additional internal reinforcement bars be placed inside hollow window sashes, such that the prior window sash latches could fasten into these bars. By eliminating the need for the reinforcement bars (not shown) to extend into the mitered corners of the sash, the sash 190 may be constructed in a less time consuming and less costly manner.
Referring now to
The high load window sash latch in the one-piece embodiment is preferably constructed from impact resistant plastic. Impact resistant plastic is lightweight, relatively inexpensive and is resistant to cracking, breaking and other damage when subject to forces and extended use. Alternately, the window sash latch may be constructed from a light-weight metal, such as, for example, aluminum, steel, or die cast zinc. In the two-piece embodiment, the window sash latch is preferably constructed from a combination of materials. The housing is preferably constructed from impact resistant plastic and the separate housing wrap is preferably constructed from a metal for increased strength. The use of other materials is expressly contemplated though.
The high load window sash latch may be employed with an otherwise conventional window system, or with a window system that includes other structural features suited to withstanding wind forces. One such structural feature is interlocking meeting rails. Referring to
Further variations may be made to the described embodiments, and some or all of the advantages of the invention may be achieved. For example, while the illustrative embodiment depicts a double-hung window, the sash latch may also be adopted for use with other types of windows, such as, for example, casement windows or single-hung windows with only one movable sash. Similarly, while the illustrative embodiment depicts various screws, it is understood that other types of fasteners, such as, for example, bolts, may be used. Further, while the illustrative embodiment shows the latch bolt positioned on or above the top surface of the window sash, it is contemplated that the latch bolt could be partially or fully recessed in a groove or channel formed in the top surface of window sash. In such a configuration, the groove or channel may partially stabilize the latch bolt. Accordingly, the foregoing descriptions are to be taken only by way of example and not to otherwise limit the scope of the invention. It is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the invention.